The MPEG-4 part 10 standard, also referred to as H.264 standard or AVC standard, describes a method for encoding a progressive video comprising a sequence of frames intended to be displayed one after the other.
The MPEG-4 part 10 standard further describes a first mode for encoding an interlaced video. This first mode is called MBAFF mode. In this mode, each pair of macroblocks are encoded with the two fields either interlaced in the two macroblocks, or separated between the two macroblocks. The choice is made for each pair of macroblocks.
The MPEG-4 part 10 standard further describes a second mode for encoding an interlaced video. This second mode is called PAFF mode. In this mode, two consecutive fields are encoded either as two separate frames or interlaced in a single frame.
For both MBAFF and PAFF modes, both interlaced and progressive coding/decoding tools are needed, which increases the complexity and the cost of the encoder and the decoder.
In a variant known as “field coding”, the fields are separated before coding and are encoded with progressive only tools. This solution is of lower complexity but requires an adaptation of a GOP structure which indicates in particular the order according to which the frames must be encoded. Specifically, a GOP structure intended for progressive video needs to be modified in a GOP structure intended for interlaced video. This is explained for instance in the paper “GOP structures for Interlaced Video” by C. Auyeung, JCTVC-K0153, 11th JCTVC meeting in Shanghai, Oct. 10-19, 2012.
There is therefore a need for new encoding/decoding tools that overcome at least in part the previous drawbacks.